Water repellent for window panes of automobiles and method of repelling water on the window panes

Abstract

The water repellent for window panes of automobiles of this invention comprises an amino group-containing polyorganosiloxane having the specific structure, an organic acid, a surfactant and an aqueous solvent, which is usable regardless of whether it is fine or rains, and can provide a uniform film having a good water repellency held for a long period.

What is claimed is: 
     
       1. A water repellent for window panes of automobiles, which comprises at least one amino group-containing polyorganosiloxane represented by the general formula (1): ##STR6## wherein R is a monovalent hydrocarbyl group having a carbon number of 1 to 20; R 1  is hydroxyl group or an alkoxy group having a carbon number of 1 to 6; R 2  is a substituent represented by the general formula (2): ##STR7## wherein each of R 3  and R 5  is a divalent hydrocarbyl group having a carbon number of 1 to 6 and each of R 4 , R 6  and R 7  is a monovalent hydrocarbyl group having a carbon number of 1 to 20, r is an integer of 0 to 3, R 3  and R 5  may be identical with or different from each other, and R 4 , R 6  and R 7  may be identical with or different from each other; each of m, p and q is an integer of 0 to 20; n is an integer of 1 to 20; and m, n, p and q meet 1≦m+n+p+q≦60; each R may be identical with or different from each other; and each R 1  may also be identical with or different from each other,   - 20parts by weight, based on 100 parts by weight of said polyorganosiloxane, of at least one organic acid,   0.1 to 50 parts by weight, based on 100 parts by weight of said polyorganosiloxane, of at least one surfactant and   1,000 to 20,000 parts by weight, based on 100 parts by weight of said polyorganosiloxane, of at least one aqueous solvent.   
     
     
       2. A water repellent for window panes of automobiles according to claim 1, wherein the amino group-containing polyorganosiloxane has a viscosity at 25° C. of 10-1,000 cP. 
     
     
       3. A water repellent for window panes of automobiles according to claim 1, wherein the aqueous solvent contains at least one selected from the group consisting of water and water-soluble organic solvents. 
     
     
       4. A water repellent according to claim 1, wherein said at least one organic acid is selected from the group consisting of at least one carboxylic acid, at least one sulfonic acid, at least one sulfinic acid, and mixtures thereof; said at least one surfactant is selected from the group consisting of at least one anionic surfactant, at least one cationic surfactant, at least one non-ionic surfactant, at least one amphoteric surfactant, and mixtures thereof; and said at least one aqueous solvent is selected from the group consisting of water, at least one aqueous organic solvent, and mixtures thereof. 
     
     
       5. A method of repelling water on window panes, which comprises coating the window panes with the water repellent for window panes of automobiles claimed in claim 1, and not conducting any post-treatment. 
     
     
       6. A method of repelling water on window panes which comprises coating wetted window panes with the water repellent for window panes of automobiles claimed in claim 1. 
     
     
       7. A method of repelling water on window panes, which comprises spraying the water repellent for window panes of automobiles claimed in claim 1 onto a a window pane, so that droplets of the water repellent form a continuous layer and then allowing the water repellent to flow down over the window pane. 
     
     
       8. A water pellent for window panes of automobiles according to claim 2, wherein the aqueous solvent contains at least one selected from the group consisting of water and water-soluble organic solvents. 
     
     
       9. A water repellent for window panes of automobiles according to claim 2, wherein the aqueous solvent contains at least one selected from the group consisting of water and water-soluble solvents. 
     
     
       10. A method of repelling water on window panes, which comprises coating the window panes with the water repellent for window panes of automobiles claimed in claim 8, and not conducting any post-treatment. 
     
     
       11. A method of repelling water on window panes, which comprises coating wetted window panes with the water repellent for window panes of automobiles claimed in claim 8. 
     
     
       12. A method of repelling water on window panes, which comprises spraying the water repellent for window panes of automobiles claimed in claim 8, onto a window pane, so that droplets of the water repellent form a continuous layer and then allowing water repellent to flow down over the window panes. 
     
     
       13. A method of repelling water on window panes, which comprises coating the window panes with the water repellent for window panes of automobiles claimed in claim 3, and not conducting any post-treatment. 
     
     
       14. A method of repelling water on window panes, which comprises coating wetted window panes with the water repellent for window panes of automobiles claimed in claim 3. 
     
     
       15. A method of repelling water on window panes, which comprises spraying the water repellent for window panes of automobiles claimed in claim 3, onto a window pane, so that droplets of the water repellent may form a continuous layer and then allowing water repellent to flow down over the window pane.